1. Technical Field
The present invention relates to an integrated sealed secondary battery wherein a plurality of cells are arranged in series, thereby forming a one-piece battery housing.
2. Description of Related Art
FIG. 14 shows a known integrated sealed secondary battery of this type disclosed in Laid-open Japanese Patent Publication No. 7-85847. Electricity-generating elements are accommodated respectively in cases 63 formed in rectangular tubular shape having a bottom, and the apertures of the cases 63 are sealed by covers 64, thereby constituting cells 62. A plurality of these cells 2 are arranged in a row, and the cases 63 of these cells 62 are tightly bound together with end plates 65 and restraining bands 66. Positive electrode terminals 67 and negative electrode terminals 68 of cells 62 pass through the covers 64, projecting upwardly, and these terminals 67, 68 are connected successively in series by electrical connection bars 69.
The mono-block rechargeable battery disclosed in Laid-open Japanese Patent Publication No. 6-215804 in which a battery housing 71 and a cover 72 made of plastics material are heat-welded is constructed as shown in FIG. 15. Side plates 73 having concave spaces on the inside thereof are heat-welded to the outside faces of opposite side walls of two battery housings 71, whereby a water-cooled jacket 74 is formed between the side walls of the battery housings 71 and the side plates 73. A cooling liquid inlet orifice 75 for supplying cooling liquid to the water-cooled jacket 74 and an outlet orifice (not shown) for discharging cooling liquid are provided at both ends of the cover 72. Numeral 76 represents a connecting trough protruding above the side plate 73 such as to communicate the orifice 75 in the cover 72 with the interior of the water-cooled jacket 74. It is further disclosed that an inlet orifice and outlet orifice are provided above the two ends of side plate 73.
Laid-open Japanese Patent Publication No. 61-45571 discloses the provision of cooling passages that pass through upper and lower portions of partitions between cells in a mono-block housing, and the provision of cooling medium inlet/evacuation headers thereabove and therebelow, separate covers being provided for each cell.
However, with the integrated sealed secondary battery of Laid-open Japanese Patent Publication No. 7-85847, since the cells are tightly bound in close contact, if the ambient temperature is high or if discharge is effected with large current, heat cannot be removed sufficiently from the cells. There is therefore the problem that the temperature of the cells rises, lowering cell life. Furthermore, since the positive electrode terminals 67 and negative electrode terminals 68 project above the cover at each cell 62, there is the problem that a sealing construction for the large number of electrode terminals and the portions where they pass through becomes necessary, resulting in increased costs.
In this regard, in the rechargeable battery of Laid-open Japanese Patent Publication No. 6-215804, rise in temperature is suppressed to some extent by cooling of the side faces of the housing 71 by the water-cooled jacket 74. Nevertheless, in the case of a secondary battery in which cells are integrated as shown in FIG. 14, the temperature rise of the cells cannot be sufficiently suppressed, because of insufficient cooling between the cells. Moreover, since the inlet orifice 75 and the outlet orifice for supplying and discharging cooling medium to and from the water-cooled jacket 74 protrude above the cover 72, there is a risk that an obstruction may accidentally strike and damage the inlet orifice 75 or outlet orifice, with the result that cooling medium may leak, making cooling impossible.
In the case of the rechargeable battery of Laid-open Japanese Patent Publication No. 61-45571, while the region where the cooling passages are formed that pass through upper and lower portions of partitions between the cells in the mono-block housing is forcibly cooled, the cooling effect is still insufficient, since the entire outside surface of the cells is not forcibly cooled. There are also the problems that, since the construction of the housing is complicated, manufacturing costs are high and, since it is necessary to provide a cover for each cell, a large number of separate operational steps are required in assembly, also raising the cost.
Consideration has been given, as disclosed in the above Laid-open Japanese Patent Publication No. 7-85847 or Laid-open Japanese Patent Publication No. 61-45571, to reducing the number of locations where sealing construction is required at the portions where the terminals pass through, by adopting a construction wherein the electrical connection between cells is effected by means of internal connecting elements. However, in this case, there is the problem that the cooling performance is further lowered, owing to the considerable amount of heat generated in the vicinity of the connecting elements.
Furthermore, in some cases, temperature sensors are provided in the space above the electrode plates of each cell in order to enable counter-measures to be taken when any of the cells reached more than a prescribed temperature. However, there was the problem that the cell temperature could not be detected accurately because of a temperature gap between the spaces and the groups of electrode plates.
In view of the above problems, an object of the present invention is to provide an integrated sealed secondary battery which is of an inexpensive construction and wherein the cells can be effectively cooled.
Another object of the present invention is to provide an integrated sealed secondary battery wherein there is no risk of damage to the orifices that supply and discharge cooling medium to and from the cooling medium passages and there is no risk of cooling becoming impossible due to leakage of cooling medium. Yet another object of the present invention is to provide an integrated sealed secondary battery wherein, even though electrical connection between the cells is achieved by internal connecting elements so as to reduce cost, the cells and the connecting elements can be effectively cooled.
The present invention provides an integrated sealed secondary battery comprising: a plurality of cells arranged in a row respectively accommodating electricity-generating elements within rectangular tubular cases having a bottom, with their upper open ends being sealed; first cooling medium passages formed on both sides of the row of the cells; and second cooling medium passages formed between the cases of the cells that communicate with the first cooling medium passages on both sides of the row of the cells.
Since all of the side faces of the cells, including those between the cells, can be forcibly cooled by the cooling medium passing through these cooling medium passages, all of the cells can be effectively cooled.
If cooling medium passages are provided on the outside of the cells at the two ends of the integrated sealed secondary battery, the outside faces of the cells at the two ends can also be forcibly cooled.
If a cooling jacket member is joined to both sides and/or both ends of the row of the cells, the cooling medium passages can be constituted easily and with light weight.
If projections are provided on at least one of mutually facing opposite wall surfaces of the cases of the cells, cooling medium passages can be formed in a simple fashion and at low cost over practically the entire surface between the opposite wall surfaces of the cells.
If flow-alignment projecting strips are provided in the cooling medium passages such that the cooling medium flows over the entire surface of the cooling medium passages on both sides of the cell arrangement direction, the whole can be cooled reliably and uniformly, thereby ensuring high cooling performance.
If the cells are mutually joined in integral fashion and their apertures are sealed by an integral cover, an integrated sealed secondary battery of a one-piece housing can be obtained with small numbers of components and assembly steps.
If the cases and cover of the cells, or the cases, cover and cooling jacket members of the cells, are respectively made of synthetic resin and are integrated by being mutually joined by welding, an integrated secondary battery of a one-piece housing can easily be obtained.
If an inlet orifice and outlet orifice for supplying and discharging cooling medium to and from the cooling medium passages are provided at both ends of the row of the cells and are connected to the cooling medium passages on both sides through distribution headers, cooling medium can be supplied and evacuated from a single inlet orifice and outlet orifice, making it possible to simplify the cooling piping of the secondary battery.
If the cooling medium passages are formed respectively between the cases of each two cells, the flow path cross-sectional area of a single cooling medium passage over its entire length can be made large, making it possible to reduce pressure losses in the cooling medium passage.
Another aspect of the present invention is that an inlet orifice and an outlet orifice for supplying and discharging cooling medium to and from the cooling medium passages are mounted in recesses of the integral cover for closing the open ends of the cell cases such as not to protrude beyond the planar external dimension of the integral cover.
Since the orifices do not protrude beyond the external shape of the cover, there is scarcely any risk of the orifices being damaged by accidentally striking an obstruction, so the risk of cooling becoming impossible due to leakage of cooling medium can be eliminated.
If the connection ports of the inlet orifice and outlet orifice are arranged in a horizontal direction, when a plurality of secondary batteries are arranged in parallel, the connecting pipes that effect connection between the orifices can be laid horizontally, so they do not protrude above the cover. The task of connecting the piping of the connecting pipes is easy and the piping can be kept compact and there is no risk of its being damaged.
The inlet orifice and outlet orifice are comprised of J-shaped box elements whose underside is open and whose planar shape is approximately J-shaped, with the connection ports projecting from the tip of the short side, so as not to protrude beyond the tip of the long side of the J-shaped box elements. These J-shaped box elements are joined to the cover, while connecting apertures communicating with the cooling medium passages are formed in the cover at positions facing to the tip of the long side of the J-shaped box elements. By this arrangement, the orifice can be mounted to the cover in such a manner that the connection ports are protected by the long side of the J-shaped box element. Furthermore, since the connecting apertures communicating with the cooling medium passages are positioned at the tip of the long side of the J-shaped orifice, the connection ports and connecting apertures can both be positioned at both ends of the secondary battery, making it possible to achieve a compact construction of the secondary battery as a whole.
Corresponding recesses are formed on one side at both ends of the cover for receiving the J-shaped box elements therein such that the long side is arranged on the outside, while the short side is arranged on the inside. Thereby, the connection ports are protected by the long side of the J-shaped box elements. Also, the overall construction of the secondary battery can be made compact, since the electrode terminals may be arranged on the other side of the cover, with the safety valves of the cells being arranged in the middle.
Yet another aspect of the present invention is that connecting elements for electrically connecting adjacent cells are disposed inside of the integral cover, and cooling medium passages are also formed above these connecting elements.
Since all of the side faces of the cells, including those between the cells, can be forcibly cooled by cooling medium passing through the cooling medium passages and the cooling passages between the cases, and furthermore the connecting elements can be cooled from above, all the cells and the internal connecting elements can be effectively cooled. Furthermore, since no differences are produced between the temperatures of the elements for electromotive force and the spaces, because the spaces above the elements for electromotive force in the cells are cooled by the cooling medium flowing through the connecting element cooling passages, precise measurement of the cell temperatures can be achieved by temperature sensors arranged in these spaces.
Cooling medium passages are constituted by joining plate-shaped cooling jacket members on both sides of the row of the plurality of cells, the upper ends of these cooling medium passages being linked to both ends of the connecting element cooling passages. Thus the cooling medium can flow through from the cooling medium passages into the connecting element cooling passages. Furthermore, the integrated sealed secondary battery can be constructed with light weight and low cost, thanks to the use of compact plate-shaped cooling jacket members.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.